高密度烃燃料雾化特性试验

Experiment on atomization characteristics of high density hydrocarbon

关键词:  直射式喷嘴  粒径分布  粒子图像测速系统

Key words:  Plain-orifice atomizer  Particle size distribution  Particle image velocimetry system

摘要:

采用试验手段研究了高密度烃燃料在直射式喷嘴情况下的雾化规律,采用数字图像处理技术,使用粒子图像测速系统(PIV)对其在横向高温气流中形成的喷雾场进行图像测量和分析。初步研究了气流温度、油压、气压与气流速度对高密度烃燃料雾化特性的影响,以及射流与喷嘴距离对喷雾粒子索太尔平均直径(SMD)的影响。试验结果显示:气流温度和油压的增加有助于提高高密度烃的雾化效果。在研究气流速度对其影响时,要考虑加热气流蒸发产生的影响,在雾化初始阶段速度因素占主导地位,而在下游距离喷嘴50~75mm间的某一位置开始,蒸发因素将起到主要作用。通过数值计算与实验比较,进一步说明了高温气流蒸发作用在颗粒二次雾化中的重要性。研究结果为优化设计高密度烃燃料发动机燃烧室提供依据。

Abstract:

The atomization characteristics of high density hydrocarbon fuel from a plain-orifice atomizer were experimentally investigated. Using digital image processing techniques, PIV were employed to measure and analyze the spray images of fuel perpendicularly injected into high temperature airflow. The effects of airflow temperature, fuel pressure, and airflow pressure and airflow velocity on atomization characteristics of the high density hydrocarbon fuel were preliminarily studied, and the effect of the distance to the orifice on SMD of atomized particles was also studied. It is concluded that the increase of airflow temperature or fuel pressure is beneficial to the atomization of high density carbon fuel. As for the effect of airflow velocity on the atomization, vaporization by heated airflow should be taken into account. In the beginning of atomization, airflow velocity is the dominant factor; however, from somewhere in the downstream about 50~75mm to the orifice vaporization effect takes over. By the comparison of simulations and experiments, the importance of vaporization effect on secondary atomization of the particles due to high temperature airflow is further demonstrated. The results of the research provide a basis for better design of combustors using high density hydrocarbon fuel.